I apology for this off topic question:
I have a 2D FT of size N x N, and I would like to reconstruct the original signal with a lower sampling frequency directly (without using an interpolation procedure): Given M < N the goal is to compute a M x M "time domain" signal.
In the case of 1D signal the trick is simple --- given a length N freq. domain Sig:
sig = np.fft.ifft(Sig, M)
This trick does not work in 2D:
sig = np.fft.ifft2(Sig, (M,M))
is far from being the right answer.
Any ideas?